All rights reserved

Monday, March 22, 2010

Hyperbaric Oxygen Therapy / Diving Accidents.

(source UHMS)

Did you always think that pressure cabines were used to treat decompression sickness only ??? Well, it does a lot more..

What is HBO ?
Hyperbaric Oxygen Therapy (HBO, HBOT) is a special medical treatment that has been successfully applied for decades and worldwide. In a hyperbaric oxygen therapy chamber, patients inhale pure oxygen through respiratory masks at a higher than atmospheric pressure. It has been proved scientifically that the amount of oxygen dissolved in blood-plasma and lymph particularly increases throughout this form of treatment compared to any other method using oxygen. Especially inflamed tissue that is insufficiently supplied with oxygen can be cured by means of this treatment which stimulates the body’s production of small blood vessels, bones and connective tissue, as well as its natural defense mechanisms. In addition, edema becomes reduced and the cells’ metabolism normalized.
These are only a few of the healing effects of Hyperbaric Oxygen Therapy (HBO). Several therapeutic principles are made use of in HBOT:
  • The increased atmospheric pressure in the chamber is of therapeutic value when HBO is used in the treatment of decompression sickness and air embolism.
  • For many other conditions, the therapeutic principle of HBO lies in a drastically increased partial pressure of oxygen in the tissues of the body. The oxygen partial pressures achievable under HBO are much higher than those under breathing pure oxygen at normal atmospheric pressure.
  • A related effect is the increased oxygen transport capacity of the blood. Under normal atmospheric pressure, oxygen transport is limited by the oxygen binding capacity of hemoglobin in red blood cells and very little oxygen is transported by blood plasma. Because the hemoglobin of the red blood cells is almost saturated with oxygen under normal atmospheric pressure, this route of transport can not be exploited any further. Oxygen transport by plasma however is significantly increased under HBO only dependant of the pressure applied.
When do you use HBO?
To support other measures for treatment of diseases
When standard treatments are not possible (contraindications etc.)
To save life, to avoid amputation and invalidity
To reduce the time for healing and hospitalisation
According to the recommendations of the involved medical scientific societies as:
Undersea and Hyperbaric Medical Society (UHMS), USA - Club Francais de Medicine Hyperbare - European Council of Hyperbaric Medicine (ECHM) – European Baromedical Society ( EUBS ) - German Society for Diving- and Hyperbaric Medicine (GTÜM), German Professional Society of Hyperbaric Chambers (VDD).
Strongly recommended indications
  • decompression sickness
  • air or gas embolism
  • carbonmonoxyd poisoning ( specially during pregnancy) to prevent neurological, psychiatric and psychological symptoms - irrespective of COHb
  • necrotising infections of soft tissues ( gas-gangrene, necrotising fasciitis, fournier-gangrene)
  • diabetic foot ulcers (selected cases)
Recommended indications
  • crush wounds, comparment syndrome and acute ischaemia (traumatic or vascular basis)
  • skin grafts and flaps (Compromised)
  • exceptional blood loss anaemia
  • refractory osteomyelitis - specially scull and sternum
  • acute acoustic trauma
  • otitis externa maligna (necroticans)
  • sudden deafness
  • ischaemic lesions in diabetes (after vascular reconstruction)
  • ischaemic atherosclerotic lesions (after vascular reconstruction)
  • bone and soft Tissue radiation necrosis (after vascular reconstruction)
  • neuroblastoma stadium IV – recidiv (after vascular reconstruction)
  • brain abscess (selected cases) (after vascular reconstruction)
  • prevention of osteoradionecrosis after tooth extraction in radiated jaws (after vascular reconstruction)
  • late radiation injury (soft tissue and bone i.e. proctitis, cystitis,
    breast swelling)
  • osteoradionecrosis spec. jaws
Optional indications
  • enhancement of healing in certain problem wounds
  • thermal burns (second degree or more)
  • post anoxic encephalopathy
  • acute opthalmologic ischaemia
  • support of implantations in radiated jaws
  • radiation necrosis (intestinal and other)
Investigational indications
  • migraine
  • cerebral palsy
  • sequelae of traumatic brain injuries
  • borreliosis (Lyme disease)
Effects of pressure
Patients inside the chamber will notice discomfort inside their ears as a pressure difference develops between their middle ear and the chamber atmosphere. This can be relieved by the Valsalva maneuver or by "jaw wiggling". As the pressure increases further, the air may become warm. When the patient speaks, the pitch of the voice may increase to the level that they sound like cartoon characters.
To reduce the pressure, a valve is opened to allow air out of the chamber. As the pressure falls, the patient’s ears may "squeak" as the pressure inside the ear equalizes with the chamber. The temperature in the chamber will fall.

Possible complications
There are risks associated with HBO, similar to some diving disorders. Pressure changes can cause a "squeeze" or barotrauma in the tissues surrounding trapped air inside the body, such as the lungs, behind the eardrum, inside paranasal sinuses, or trapped underneath dental fillings. Breathing high-pressure oxygen for long periods can cause oxygen toxicity. Temporarily blurred vision can be caused by swelling of the lens, which usually resolves in two to four weeks. There are reports that cataract may progress following HBO.

Diving Accident


When scuba diving, additional oxygen and nitrogen dissolve in body tissues. The additional oxygen is consumed by the tissues, but the excess nitrogen must be washed out by the blood during decompression. During or after ascent this excess nitrogen gas can form bubbles in the tissues, analogous to the carbon dioxide bubbles that form when a carbonated beverage container is opened. These bubbles may then cause symptoms that are referred to as
decompression sickness (“DCS” or “the ”).

Trapping of gas within the lungs during ascent, either because the lung is diseased or because of breath-holding, can cause bubbles to be forced into the bloodstream (“arterial gas embolism” or “AGE”), where they can block the flow of blood or damage the lining of blood vessels supplying critical organs such as the brain. AGE can also occur in non-divers, due to entry of air into the body, such as during medical diagnostic or therapeutic procedures. Symptoms of DCS or AGE can include joint pain, numbness, tingling, skin rash, extreme fatigue, weakness of arms or legs, dizziness, loss of hearing, and in serious cases, complete paralysis or unconsciousness. There can be weakness or paralysis in the limbs; vision can be impaired or absent; brain, heart, lung and other organ damage may occur. Limited use of remaining functions can be sufficiently severe that total disability results. Those who do not die may be limited to walking with canes, crutches or walkers. Those more severely disabled may be wheelchair confined or bedridden. These outcomes may be permanent and may severely impact quality of life. Maximal medical treatment of the condition is necessary to ensure the best possible degree of recovery from this potentially disastrous problem Emergency treatment of DCS or AGE includes administration of oxygen and measures to maintain adequate blood pressure, such as lying the patient down and fluid (either oral or intravenous, depending upon availability and severity of the illness). Definitive treatment for DCS or AGE is administration of 100% oxygen at increased atmospheric pressure in a hyperbaric chamber (typically at a pressure 2-3 times greater than normal atmospheric pressure).
While some delay in transporting a patient to a hyperbaric chamber is usually unavoidable, the success in relieving symptoms is greater if the treatment is administered within a few hours after the onset of symptoms. Some improvement might be expected, particularly in mild cases, even after a day or more of delay.
Hyperbaric oxygen has been shown to reduce the size of bubbles obstructing circulation. The increased pressure in the hyperbaric chamber reduces bubble size and drives the remaining gas into physical solution, while the high oxygen pressure washes out inert gas from the bubble. When bubbles are smaller or resolved, blood flow resumes. Poorly oxygenated tissues then receive higher levels of oxygen delivery. Another problem in gas embolism is that vessels obstructed by bubbles may leak fluid into surrounding tissues, resulting in swelling. Such swelling can further reduce tissue blood flow. When flow is restored, the local swelling will subside with resultant improvement in circulation and oxygen supply. Finally, the high levels of oxygen provided in the hyperbaric chamber have the potential to immediately restore cellular oxygen levels while blood flow impairment and tissue swelling are being corrected.
Hyperbaric oxygen treatment is the primary treatment for gas embolism and a major review of reported cases clearly indicates superior outcomes with its use compared to non-recompression treatment
The vast majority of cases respond satisfactorily to a single hyperbaric oxygen treatment. Sometimes, repetitive treatments are recommended until no further improvement can be observed. A small minority of divers with severe neurological injury may require 15-20 repetitive treatments. The success of hyperbaric oxygen treatment for DCS or AGE has borne the test of time, and continues to be the standard of care for the treatment of these disorders.
Hyperbaric oxygen treatment is the primary treatment for gas embolism and a major review of reported cases clearly indicates superior outcomes with its use compared to non-recompression treatment.

text is taken from UHMS

No comments: